A technique has been known from the past of using a long plate-shaped magnet formed by integrating a plurality of divided magnet parts, as a magnet to be inserted into magnet insertion slots of a rotor core of a motor (see WO2001/095460A). By forming the magnets to be inserted into the magnet insertion slots with the plurality of magnet parts as mentioned above to reduce volume of the individual magnet parts, it is possible to reduce the eddy current generated by the variation of an acting magnetic field.
Since a large cost is incurred for bonding the plurality of the magnet parts to form the long plate-shape, a method is considered for cost reduction in which a bonding process of the plurality of the magnet parts is omitted and a plurality of the magnet parts is inserted into the magnet insertion slots of the rotor core as it is.
However, if an attempt is made to insert the magnet parts into the magnet insertion slots of the rotor core as they are, the weight of one magnet part is smaller as compared with a case in which the long plate-shaped magnet is inserted, and thus dropping energy at the time of magnet insertion will become smaller by the same amount. Consequently, this leads to a problem that when a magnet part contacts a side wall of the magnet insertion slot, the magnet part would tilt in its pose due to friction resistance thereof and the magnet part would readily be caught up in the middle of the magnet insertion slot.